Full-time flood protection control for dishwasher

Abstract

A dishwasher control circuit including a single-pole, double-throw door interlock switch and a water level sensing means, which sensing means includes a single-pole, double-throw switch. The sensing means switch connects the water inlet valve control solenoid and the drain valve control under normal operating conditions, and connects in series a direct power line and the pump motor and drain solenoid during flooding conditions. The control provides continuous protection against flooding in the dishwasher.

Having thus described the invention, what is claimed is: 
     
       1. An automatic dishwasher having a washing enclosure, a pump and motor assembly to circulate water within said enclosure, a dishwasher fill means including a high-impedance solenoid-controlled water inlet valve for supplying liquid to the enclosure, a low-impedance electrical control component to control the flow of liquid from the enclosure, and a control system comprising: a single-pole, double-throw door interlock switch;   a timer including a motor and three cam-actuated switches, one of said switches controlling the power to the timer motor, another controlling the power to the motor and pump assembly, and the third controlling the power to the solenoid control of the water valve and drain valve;   a water level sensor, independent of the dishwasher fill means, including a switch, said water level sensor switch being of the single-pole, double-throw type and connecting the high-impedance solenoid and said low-impedance electrical control component in series during normal operation and connecting said motor and pump assembly to a power supply during flooding conditions;   further, said single-pole, double-throw door interlock switch functioning to supply power from said water level sensor switch to said motor and pump assembly when the door is in its unlatched position.   
     
     
       2. The dishwasher of claim 1 wherein said low-impedance electrical control component is a solenoid controlled outlet valve. 
     
     
       3. The dishwasher of claim 1 further comprising an electrical heating element to facilitate drying of articles within said washing enclosure. 
     
     
       4. The dishwasher of claim 1 wherein said water level sensor switch includes a float having first and second operative positions and being located to move to said second operative position as the liquid level within the washing enclosure exceeds a predetermined height, the float, when in said first position allowing energizing of said inlet valve, but, when in said second operative position energizing said pump and motor and preventing energization of said inlet valve. 
     
     
       5. The dishwasher of claim 2 wherein said control system includes at least two switches, the first switch controlling power flow to said pump and motor assembly under normal operating conditions, and the second switch controlling power flow to both the low-impedance drain solenoid and the high-impedance water inlet valve, said two switches being positioned to be preselectively actuated thereby providing that the second switch can transmit power reversibly therethrough to said motor and pump assembly when said first switch is open. 
     
     
       6. The dishwasher of claim 1 wherein said low-impedance electrical control component is a low-impedance drain pump motor.